Increasing energy costs and environmental concerns have emphasized the need to produce sustainable renewable fuels and chemicals. Fatty acids are composed of long alkyl chains and represent nature's “petroleum,” being a primary metabolite used by cells for both chemical and energy storage functions. These energy-rich molecules are today isolated from plant and animal oils for a diverse set of products ranging from fuels to oleochemicals.
Whereas microbial fermentation processes for producing ethanol and related alcohol biofuels are well established, biodiesel (methylesters of fatty acids) is the major long chain product produced biologically, and it is almost exclusively derived from plant oils today. However, slow cycle times for engineering oil seed metabolism and the excessive accumulation of glycerol as a byproduct are two major drawbacks of deriving biodiesel from plants. Although most bacteria do produce fatty acids as cell envelope precursors, the biosynthesis of fatty acids is tightly regulated at multiple levels and large quantities are not made. Thus, the production of fatty acids from bacteria has not yet reached the point where it is cost effective.
The ability to produce free fatty acid at high yields and high rates by the metabolically engineered strains would provide an efficient framework to produce a large class of other derived products (chemicals and biofuels) either biologically or chemically. For example, as shown in FIG. 1, by introducing additional appropriate pathways, fatty acids can be converted to chemicals such as hydrocarbons, fatty alcohols, hydroxyl fatty acids, dicarboxylic acids etc. Likewise, the omega-end of the molecules can be modified by changing the starting precursors in the initial step of the fatty acid biosynthesis pathway (marked by white block arrows). Furthermore, the chain length of these molecules can be changed by using appropriate acyl-ACP thioesterases specific to a particular chain length, such as C8, C10, C12 or C14. In addition, various molecules can also be tapped out at different points during the fatty acid elongation cycle.
U.S. Pat. No. 7,759,094 discloses a method for the production of L-amino acids by fermentation of genetically engineered microorganisms, in which fadR is overexpressed and sucC is also overexpressed. However, there is no teaching with regard to the production of fatty acid in this patent.
U.S. Pat. No. 7,553,645 discloses a process for preparing L-amino acids using a genetically engineered or transformed microorganism, in which sucC is overexpressed. However, there is no teaching with regard to the production of fatty acid in this patent.
U.S. Pat. No. 7,211,415 also discloses a process for producing L-amino acids by fermentation of genetically engineered microorganisms of the Enterobacteriaceae family, in which sucC is overexpressed. However, there is no teaching with regard to the production of fatty acid in this patent.
US20110195505 discloses a genetically engineered lactobacillus for butanol production, in which deletion at fabZ1 results in 10% increase in total cell membrane saturated fatty acids. However, there is no teaching regarding the effect of fabZ overexpression on the production of fatty acids.
US20080160585 and US20080038787 disclose a method of increasing the production of lysine from a microorganism, in which sucC is deregulated. However, no detail was disclosed as to what extent of deregulation is involved, such as overexpressed, reduced or inactivated, nor on how to achieve the deregulation.
US20060046288 discloses a mutant E. coli strain with increased succinic acid production, in which it has reduced activity of fadR gene. However, no detail regarding the fadR gene or the regulation/mutation thereof is specifically disclosed.
WO2011116279 discloses hybrid ACP thioesterases, which can be combined with deletions in native fadD, and sucC. They also teach acidifying the medium to increase production of fatty acids.
Therefore, there is a need in the art for a biological system of producing fatty acids that is more efficient and cost effective than heretofore realized.